I'm very sorry to hear about your sister and the difficult changes she is going through. The fact that both your sister and father got
ALS suggests that it is the "familial" type which is genetic and inherited. However, since your mother's family was very probably OK, there is a 50-50 chance whether you inherited the gene for it. You sister was unlucky and inherited it, but that doesn't say anything about whether it happened to you.
The impression I have from my reading is that if you did inherit the gene for
ALS, you will probably get it if you live long enough. If you didn't inherit it, your chances of getting
ALS are extremely small. I don't think there is any reliable genetic test for this at present. Even among familial
ALS, they can only identify known genes in about 20% of cases. So they might be able to test you and tell you that you do carry a gene which is known to be bad and will probably get
ALS someday; but they can't give you a guarantee that you are OK. Not enough is known at present for the genetic test to be very informative.
The various environmental exposures to radiation, metals, toxins, etc, probably don't change the eventual outcome. Maybe they would affect the timing. How old were your father and your sister when they got it, and how old are you? If you live substantially past those ages then that would be a good sign that you didn't inherit the gene.
The symptoms you describe don't sound much like
ALS, which is slower and seldom shows improvement. However I did read that familial
ALS in particular is more likely to be preceded by unusual neurological manifestations such as pain and tingling. Of course, many people do experience various neurological troubles over the course of their lifetimes, without having
ALS. Our bodies aren't perfect and things do go wrong from time to time. So your experiences certainly don't mean you are going to get
ALS.
The remaining question is, are there things you can do to extend your healthy lifetime, in case you did inherit the gene for
ALS? Unfortunately I don't think there is much known on this question. Probably it wouldn't hurt to try some of the same nutritional strategies as for PALS (People with
ALS). Many of us take antioxidant supplements and vitamins as the disease is known to involve oxygen-related damage to the nerve cells. You can search on the forums here to see some of the supplements people have tried.
Again, bear in mind that even though your father and sister got
ALS, you may very well have been lucky and escaped the bad gene. Try not to let your current neurological symptoms worry you too much. Unless or until you start to experience the gradual weakness and other symptoms that are characteristic of
ALS, you can try to remain hopeful and optimistic. I know it must be heartbreaking to see your sister's difficulties, with the added fear that you might experience the same thing someday. I am very sorry that you have to be going through this.